Crackle, no post

I recently changed the case of my rig + now the mobo doesn't work.
The power light comes on when plugged in. When i turn it on, the fans spin but i get no post. the speaker just crackles.
I've tried different ram in each dimm + still no post. even with no ram.
i changed the case back to its original but still crackles.
All the hardware appart from the motherboard still works.

motherboard: ASUS P5N-T
CPU: Pentium dual core 2.6ghz
RAM: 2x1gb OCZ Reaper 8500
GPU: 8800GTS 512
PSU: 750W cheap thing + 450W Thermaltake Power Express (for 1gpu)

I have tried using my other 8800GTS, 2x1gb Reaper, 2x1gb Crucial Ballistix + Q6600 cpu aswell, but still no luck. :(

3 answers Last reply
More about crackle post
  1. Can anyone tell me whats happened, if its fixable or a dead board :)
    TY x
  2. Welcome Newcomer! :)

    Initially, seemed like a short but reading further I changed my mind to your PSU.

    Strip the MOBO to its bare minimum, connect (1) PSU, clear CMOS if it will now post or unplug + remove CMOS battery ~ 15 minutes.
  3. If what jaquith suggested (do the simple stuff first), start over.

    Strip everything out of the new case and start over with one PSU and one video card.

    Work through our standard checklist and troubleshooting thread:
    I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

    If not, continue.

    I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

    Breadboard - that will help isolate any kind of case problem you might have.

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

    Make sure you plug the CPU power cable in. The system will not boot without it.

    I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

    You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

    At this point, you can see if both PSU's will work on a minimum load.

    If no beeps:
    Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

    At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

    The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

    You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

    This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

    If the system beeps:
    If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

    Silence or long single beeps indicate a problem with the memory
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